Question: $-\dfrac{4}{10} - \dfrac{3}{5} = {?}$
Answer: $ = - {\dfrac{4 \times 1}{10 \times 1}} - {\dfrac{3 \times 2}{5 \times 2}} $ $ = - {\dfrac{4}{10}} - {\dfrac{6}{10}} $ $ = - \dfrac{{4} - {6}}{10} $ $ = -\dfrac{10}{10}$